1. Field of the Invention
The present invention relates to a cooling apparatus for a computer storage unit or an electronic board mounting an LSI and other electronic devices to be mounted on an electronic equipment or an electrical power equipment. More particularly, the invention relates to a compact water vaporization type cooling apparatus excellent in cooling property, which permits inhibition of a temperature increase by eliminating heat generation from electronic parts or a computer storage unit, and ensures normal operation even in an environment of a temperature over the maximum working temperature of an electronic equipment.
2. Description of the Related Art
For the purpose of cooling electronic parts including LSI mounted on an electronic equipment or an electrical power equipment, it has been the conventional practice to dissipate the heat generated from heating members such as an LSI through combination of a refrigerant bag and a heat pipe, as disclosed, for example, in Japanese Unexamined Patent Publication No. 6-21,279.
FIG. 8 is a configuration diagram illustrating a conventional heat transfer apparatus, for example, disclosed in Japanese Unexamined Patent Publication No. 6-21,279.
In the drawing, a protective metallic container 1 has an opening 2 provided in the bottom thereof. A refrigerant bag 3 is housed in the lower part of the protective metallic container 1. The refrigerant bag 3 has a configuration in which the both ends of a cylinder made of a soft plastic material such as polyethylene are sealed by heat sealing, and filled with an operating liquid 4, with the upper space filled with a gas. When this refrigerant bag 3 is housed in the protective metallic container 1, a part of the refrigerant bag 3 projects from the opening 2, and there is formed a contact portion 5 coming into contact with an object 8 of cooling such as the LSI.
Further, a heat transfer pipe 6 is housed in the protective metallic container 1 as if it were wrapped by the refrigerant bag 3. A radiator fin 7 is attached to an end of the heat transfer pipe 6 projecting outside from the protective metallic container 1.
Applicable operating liquids 4 include halogen-based solvents such as flon and p-fluorocarbon (C.sub.6 F.sub.4).
Operations of the conventional heat transfer apparatus will now be described.
The heat transfer apparatus is installed so that the contact portion 5 comes into contact with the object 8 of cooling such as an LSI. Heat generated by the object 8 of cooling is transferred from the contact portion 5 to the operating liquid 4. The operating liquid 4 is evaporated by the heat transferred from the contact portion 5. The thus generated vapor rises up through the upper space of the refrigerant bag 3, and upon reaching the portion in contact with the heat transfer pipe 6, the heat is absorbed by the heat transfer pipe 6 there, the condensed vapor being liquefied and dropping. Through this exchange of latent heat, the heat is absorbed by the heat transfer pipe 6. Then, the heat is dissipated from the radiator fin 7 provided at an end of the heat transfer pipe 6. By repeating this process of heat exchange, the object 8 of cooling is cooled.
In the conventional heat transfer apparatus having the configuration as described above, the object 8 of cooling cannot be cooled beyond the outer periphery temperature of the radiating section, and therefore, the apparatus cannot be operated in an environment including a temperature of over the maximum working temperature of the electronic equipment. There is therefore a problem of limited environments of use.
Since a halogen-based solvent such as flon or perfluorocarbon is used as the operating liquid 4, the refrigerant must be collected upon abolishing the apparatus for environmental protection purposes. However, many of electronic equipments are supplied to a market composed of unspecified users, and this has posed the problem of establishing a method of collection.
In general, an electronic equipment should meet the requirement for downsizing. The aforementioned structure of the heat transfer apparatus however comprises many components near the board, and this has prevented the problem of downsizing from being solved.
The object 8 of cooling is in mechanical contact with the refrigerant bag 3. This results in a large contact heat resistance, leading to a further larger heat density. As a result, there is posed another problem of impossibility to take sufficient actions to satisfy the requirement for a cooling method excellent in cooling performance.